A technique of forming a film on a substrate by alternately supplying a source gas and a reactive gas as process gases onto the substrate is one of processes included in a process of manufacturing a semiconductor device (see Japanese Patent Laid-open Publication No. 2012-142367 and Japanese Patent Laid-open Publication No. 2012-134311).
As semiconductor devices become finer, surface areas of wafers become increased and more fine treatments are required to form a film in deep grooves or the like. Also, in order to improve the manufacturing throughput of a semiconductor device, the size of a process chamber in which wafers are accommodated becomes greater as wafer sizes become larger or the number of wafers to be processed increases. Thus, the supply rate of a process gas is required to be increased so as to uniformly process such a large-sized wafer.